IL4

IL4 Full Name

Interleukin 4

IL4 Introduction

Interleukin-4 (IL-4) is a pleiotropic cytokine, a key signaling molecule of the immune system, primarily secreted by activated CD4+ T helper type 2 (Th2) cells, mast cells, basophils, and eosinophils. It is a glycoprotein with a molecular weight of approximately 20 kDa. IL-4 signals through a receptor complex consisting of the IL-4 receptor α (IL-4Rα) chain paired with either the common γ chain (γc, forming the Type I receptor) or the IL-13 receptor α1 chain (forming the Type II receptor), leading to the activation of the JAK-STAT signaling pathway, principally STAT6. Its discovery marked a fundamental understanding of the bifurcation of T-cell immune responses.

Figure 1. Strcuture of Interleukin-4.

Primary Immunological Functions
IL-4 is the principal cytokine responsible for driving the differentiation of naïve CD4+ T cells into the Th2 cell lineage. It defines Th2-type immune responses by promoting antibody class switching in B cells to produce Immunoglobulin E (IgE). Furthermore, it enhances the expression of major histocompatibility complex (MHC) class II molecules and CD23 on B cells, stimulating their proliferation. IL-4 also inhibits the development of pro-inflammatory Th1 cells and the production of their associated cytokines (e.g., IFN-γ), establishing a critical regulatory balance in adaptive immunity.

Role in Physiology and Disease Pathogenesis
Physiologically, IL-4 is essential for host defense against extracellular parasites, such as helminths, by orchestrating the IgE- and eosinophil-mediated response. However, its dysregulation is centrally implicated in the pathogenesis of allergic diseases, including asthma, atopic dermatitis, and allergic rhinitis. The overproduction of IL-4 leads to excessive IgE synthesis, mast cell activation, and airway hyperresponsiveness. Its role also extends to certain autoimmune conditions and tumor biology, where it can sometimes exhibit both pro-tumor and anti-tumor activities depending on the context.

Alternate Names for IL4

IL4; interleukin 4; BSF1; IL-4; BCGF1; BSF-1; BCGF-1; interleukin-4; binetrakin; pitrakinra; B cell growth factor 1; interleukin 4 variant 2; B_cell stimulatory factor 1; lymphocyte stimulatory factor 1; 6A1